I still cannot understand how they get done with the detour in the dark and reach the Uturn sign in the daylight. Especially when Margie and Luke got there in the dark, ruling out an HOO.
From the sightings, the train arrives at 5:18am. I believe the teams all made it onto:
L9034/9031 dep. Lijiang 19:05 / arr. Kunming 5:13 (found here
). Kent/Vyxsin arrived in Lijiang at 8:15 that morning, giving them about 11 hours to complete the leg. Even with a meltdown and passport drama, there's enough time for them to complete the leg and get to the station.
Back in Kunming, sunrise on that day was at 7:36am, which would allow for a team to complete a Detour quickly (hence why M/L might have reached the U-Turn in pre-dawn and in fact, the sky was lightening up). Moreover, the time period just before dawn can have fairly volatile changes in light in a very short amount of time, so even though the girls complete it in the "dark", it might turn light by the time they get to the U-Turn.